Re: "A method for estimating HIV transmission rates among female sex partners of male intravenous drug users".
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Epidemiologic Methods↗
Biomedical subjects
R Allard
Publications and source records attributed to R Allard.
Knowledge and beliefs of international travellers about the transmission and prevention of HIV infection.
OBJECTIVES: To measure the perceived risk of acquired immunodeficiency syndrome (AIDS) among international travellers, to measure their knowledge of the transmission and prevention of HIV infection abroad and to identify some of the determinants of this knowledge. DESIGN: Survey. SETTING: Travellers' immunization clinic providing mostly primary preventive care to international travellers. PARTICIPANTS: All clients aged 18 to 50 years seen at the clinic between Oct. 2 and Dec. 21, 1989, before their departure. MAIN OUTCOME MEASURES: Sixteen statements measured knowledge of transmission and prevention of HIV infection. Standardized scales measured health beliefs. RESULTS: The response rate was 81% (331/409). Compared with other diseases AIDS was perceived to be associated with a low risk except by those travelling to countries with a high prevalence of AIDS. Most of the clients were found to have a good knowledge of HIV transmission to travellers, although some myths remained popular and some real routes of transmission, especially blood, remained underrated. In all, 70% of the subjects believed in the efficacy of condoms when used with local people, as compared with 79% when used with other tourists; this difference was greatest among travellers who perceived AIDS as being particularly severe but difficult to prevent. The determinants of the knowledge of HIV transmission and prevention were a high level of education, a mother tongue other than French, unmarried status, a high prevalence of AIDS at the destination, the duration of the trip and a high perceived risk of HIV infection. CONCLUSIONS: Counselling should teach travellers (a) not to underestimate their risk of HIV infection during their trip, (b) to decrease the risk of requiring health care in developing countries and (c) to rely on their own prudent sexual behaviour rather than on their assessment of the level of risk posed by the environment.
Acquired Immunodeficiency Syndrome↗
Intensive follow-up does not decrease the risk of repeat suicide attempts.
We carried out a randomized controlled trial to determine whether an intensive intervention after a suicide attempt could decrease by half the risk of a repeat attempt in the following two years. After initial assessment and randomization, experimental subjects attended 18 therapy appointments over one year, including one home visit, and measures to improve attendance. Control subjects received the usual care. Of 63 experimental subjects, 35% made a repeat attempt, and so did 30% of 63 control subjects. The study had a 99% power to detect the desired decrease of risk (30% to 15%). Clearly, the intervention did not achieve its objective.
Adult↗
Predictors of chlamydial infection and gonorrhea among patients seen by private practitioners.
OBJECTIVE: To identify the predictors of chlamydial infection and gonorrhea among patients tested by general practitioners. DESIGN: Prospective study. SETTING: General private practice, family planning and abortion clinic, adolescent clinic, sexually transmitted disease (STD) clinic and community health clinic in downtown Montreal. PATIENTS: The 2856 patients were included because of symptoms compatible with an STD, a history of sexual contact with a person known or suspected to have chlamydial infection, a history of a nonexclusive sexual relationship or presentation for an abortion. MEASURES: Patient information was obtained by the attending physician on a standard form. Enzyme immunoassay (EIA) for Chlamydia trachomatis and culture for Neisseria gonorrhoeae were performed on cervical (female) or urethral (male) samples. Stepwise logistic regression was used to identify the predictors of infection. RESULTS: The EIA results were positive in 11.1% of the cases and the culture results in 2.3%. Among the males chlamydial infection was independently associated with low age (odds ratio [OR] = 0.88 per year), heterosexuality (OR = 4.99), urethral discharge (OR = 3.74) and the absence of a history of gonorrhea (OR = 0.51). Gonorrhea was associated with urethral discharge (OR = 24.3) and homosexuality (OR = 3.68). Among the females chlamydial infection was associated with low age (OR = 0.79 per year), a history of sexual contact with a person known to have chlamydial infection (OR = 2.30), multiple sexual partners in the previous 12 months (OR = 1.60) and a reason for the test other than screening purposes (OR = 0.60). Gonorrhea was associated with a reason other than screening (OR = 0.24) and low age (OR = 0.74 per year). Among the patients tested for screening purposes age was the only significant predictor of chlamydial infection (OR = 0.79 per year), and the prevalence of gonorrhea was 0.4%. The actual rate of chlamydial infection was 11.8% among the patients younger than 25 years, 5.7% among those 25 to 34 years and 0.6% among those over 34. CONCLUSIONS: Age alone can be used as a criterion to screen for chlamydial infection among asymptomatic patients without a history of sexual contact with a person known or suspected to have such infection and with a history of a nonexclusive relationship. The prevalence in our population justifies screening people up to 34 years of age.
Adolescent↗
A family of mathematical models to describe the risk of infection by a sexually transmitted agent.
Several recent publications have used, without demonstrating its derivation, a mathematical model that describes the risk of being infected by a sexually transmitted agent as a function of four parameters: the number of partners, the number of contacts with each partner, the per-contact probability of transmission, and the probability of a partner being infected. The model is derived both from elementary probability concepts and, more formally, by using the binomial expansion and conditional probabilities. The assumptions involved in these derivations are brought out, as are the limitations they impose on the uses of the model. The model equations used so far in published studies are shown to be special cases of a general form that allows for more variability of the sexual behavior modeled. The different uses to which the model has been put are categorized, and some further ones are suggested.
Acquired Immunodeficiency Syndrome↗
A mathematical model to describe the risk of infection from sharing injection equipment.
A mathematical model is presented that describes the probability of a subject becoming infected as a result of sharing equipment used for percutaneous injections. This risk is a function of (a) the number of syringes shared by the subject, (b) the probability of a syringe becoming contaminated after being used once by an infective person, (c) the probability of a person becoming infected after using a contaminated syringe once, (d) the number of persons who have previously used each syringe shared by the subject, (e) the prevalence of infectivity in the group from which these previous users are drawn, (f) the number of times each syringe has been used by each previous user, and (g) the number of times the subject uses it. Simulations with the model suggest mainly that (i) when each shared syringe has been used previously by only one person, the number of persons with whom syringes are shared is more important than the number of syringes; (ii) the reverse is true when each shared syringe has previously been used by many persons; and (iii) for an equal number of injections, the "shooting gallery" type of sharing can be much more risky than other kinds of sharing, but this difference decreases as the infections becomes more prevalent.
Humans↗
HIV seroconversion in the U.S. Army.
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HIV Seropositivity↗
Renaming AIDS: 'retroviral immunodeficiency'?
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Acquired Immunodeficiency Syndrome↗
Beliefs about AIDS as determinants of preventive practices and of support for coercive measures.
We performed a telephone survey to explore relations between knowledge, beliefs (as defined in the Health Belief Model) and reported AIDS-preventive practices in a sample of 1,072 persons ages 18-65, living in the Montreal health region. AIDS-preventive practices were more frequent among the young or single, and among those with one of four health beliefs: perceiving oneself as particularly susceptible to AIDS, perceiving the disease as particularly severe, perceiving it as particularly amenable to prevention, and having a strong general health motivation. Support for coercive measures to control the AIDS epidemic was widespread but was stronger among the less educated, married people, and those with a high level of one of the following beliefs about AIDS: perceived severity, susceptibility, curability, or barriers to treatment. AIDS-preventive practices and support for coercion under epidemic conditions share their most important modifiable determinants: perceived severity of AIDS and perceived susceptibility to it. This finding suggests that emphasizing them, as is done so often in public educational campaigns about AIDS, may indeed promote preventive practices, but may also unwittingly increase support for coercive measures toward people with the disease or at high risk of it.
Acquired Immunodeficiency Syndrome↗
Comparative study on the composition of the organic matrix of the long bones of the "normal" rat and of the mutant Op/Orl.
The organic matrix of the long bones of the "normal" rat strain and of its mutant Op/Orl were investigated. This latter strain exhibits some anomalles similar to Albers-Schönberg disease as well as tooth retentions. Bones (tibia, femur) were incubated with 14C-glucose and also submitted to a fractional extraction procedure (EDTA, urea) to separate soluble and insoluble fractions. The proteins, hexoses, hexosamines, hydroxyproline content of these fractions was determined as well as the radioactivity of the soluble extracts Glycosaminoglycans were also studied by cellogel electrophoresis after pronase digestion of the EDTA-extracts. Male and female animals of each strain were studied separately. The relative amount of soluble proteins (EDTA + urea extracts) was the same in both strains, the mineral content of the final residue was however higher in the mutant Op/Orl strain. The hydroxyproline content of the mutant-extracts were lower than in the original strain suggesting a lower soluble collagen content. This may be due to a faster polymerisation, insolubillisation of freshly synthesised collagen. The hexosamine content of the mutant urea extracts and the final residue was higher than that found in the analogous extracts obtained from the normal "normal" strain, suggesting a higher proportion of structural glycoproteins in the mutant bone, uronic acid being low or absent. Some other parameters were identical between the mutant and original strains but differed between males and females. The radioactivity of the soluble extracts was higher in the males than in females. The glycosaminoglycans of the EDTA extracts are also different: male-extracts show two bands on cellogel electrophoresis, one corresponding to chondroitin-sulphate, the other to hyaluronate. Females showed only the chondroitin sulphate band. The aminoacid composition of the insoluble residue of males was higher in basic amino acids (lysine, histidine, arginine) than the female extracts. These results indicate the existence of discrete well defined differences between the organic matrix of the orginal and mutant strain on one side and between male and female bones on the other side.
Amino Acids↗
Biochemical studies on dacron arterial prostheses.
Dacron arterial prostheses, treated or not with biopolymers (gelatin, glycosaminoglycans) were implanted in the abdominal aorta of dogs and the connective tissue synthetised inside and outside the prosthesis was studied. After 3 and 9 months of implantation the prosthesis, a joining portion and a piece of aorta were excised and put in organ culture with 14C-lysine for 3 days. Representative macromolecular extracts were then obtained by a "chemical dissection" procedure. The radioactivity and the chemical composition of these extracts was studied. The DNA content of the prosthesis was higher than that of the adjacent aorta showing a dense cellular repopulation of the prosthesis. This was confirmed by histology also which revealed the presence of a newly formed limiting elastic membrane and the presence of numerous elastic fibrils. Collagen, elastin and glycosaminoglycans could be detected in the macromolecular extracts showing that the cells which repopulated the prosthesis expressed a complete biosynthetic capacity as far as matrix macromolecules are concerned. The distribution of proteins in the extracts was as follows: 4% of total proteins were extracted in a 1M CaCl2-buffer 80% of total proteins in the collagenase extracts, 10% in the 6M urea extract. Only 0,2% of proteins were in the final elastase extract, 10 times less than in the joining aorta fragment. The proportion of the other proteins was similar in aorta and in the prosthesis as well as the chemical composition (hexosamine and hydroxyproline content) of the extracts. The proportion of collagenase-extractable proteins decreased with the time of implantation (from 3 to 9 months) and the proportion of urea-extractable proteins increased. This type of modification is similar to that found in aging aorta wall. 14C-lysine was actively incorporated in all macromolecular fractions studied. The incorporation pattern of the prothesis tissue was similar to that found for the joining host aorta, showing a similar regulatory tendency for matrix macromolecules. It appears therefore that a valid hemocompatible vascular type of connective tissue can be synthesised on the dacron arterial prosthesis and nature of this connective tissue can be influenced by previous biopolymer treatment of the synthetic prosthesis. The described procedure (incorporation of labelled precursors in organ culture) appears to be a valid method for the exploration of the regulatory processes underlying the synthetic capacity for matrix macromolecules of the newly formed tissue in the synthetic prosthesis.
Animals↗
[Structural and biochemical alterations of human diabetic dermis studied by H-lysine incorporation and microscopy].
The alteration of the structural organization of dermal connective tissue was studied by light and electron microscopy and by biochemical techniques in normal human and in diabetic patients using skin biopsies. Part of the tissue was used for light and electron microscopy, the rest was incubated in the presence of 3H-lysine for four hours. The 3H-lysine labelled biopsies were submitted to a sequential extraction procedure in order to obtain representative macromolecular fractions containing the matrix macromolecules. The extracts were analyzed for their chemical composition and radioactivity. Electron microscopy revealed ultrastructural modifications of the fibroblasts, of the collagen and elastic fibers in the diabetic dermis. Fibroblasts contained an increased amount of electron dense deposits in the cytoplasm and dilated endoplasmic reticulum. The collagen bundles were dissociated. Elastic fibers under the epithelial basal laminae were fragmented or absent. The incorporation pattern of 3H-lysine into these macromolecular fractions was different in the normal and diabetic skin biopsies. The percentage of total radioactivity incorporated increased significantly in the 1M CaCl2 extractable fraction an in the 6M urea extractable fraction and decreased significantly in the collagenase and elastase extracts in diabetic skin biopsy. These results demonstrate the existence of morphological and biochemical alterations in diabetic connective tissue (dermis) reflecting alterations in the relative rates of synthesis and/or degradation of the intercellular matrix macromolecules as well as of their microarchitectural arrangement.
Adolescent↗
Biosynthesis of elastin and other matrix-macromolecules in veinous arterial prosthesis.
Homologous saphenous veins where implanted in the arterial circilation (femoral artery) of dogs for various times (1 to 9 months, most data given for 3 months). After this period, the in vitro biosynthesis of intercullar matrix macromolecules was studied by incubating the veins in organ culture conditions in the presence of 14C-lysine for 3 days. A fractional extraction procedure was used to obtain representative macromolecular extracts for the determination of chemical composition (hydroxyproline, hexosamines) and radioactivity. Neosynthesis of elastin was considered as valid criteria for the adaptation of the veinous wall to the new (arterial circulatory) conditions. The chemical composition of the grafted veins was different from that of the nongrafted, controlateral saphenous veins suggesting a molecular remodeling of the grafted veinous wall. Radioactive lysine was incorporated in all macromolecular fractions of grafted and control veins. The specific radioactivity of the extracts obtained from grafted veins was higher than that obtained from the control veins. The only exception was the collagenase extract (containing mainly the polymeric collagen) which had a somewhat lower radioactivity in the grafted vein. The incorporation of lysine in the elastin fraction increased by a factor 10 in the grafted vein as compared to the non-grafted veins. Radioactive desmosine could be demonstrated in the elastin fraction. It appears therefore that the veinous wall could adapt its biosynthetic capacity to the new circulatory conditions by increasing considerably the biosynthesis of elastin. This is accompanied by an increase of the synthesis of other macromolecules and a significant remodeling of the macromolecular structure of the vessel wall.
Animals↗